Telephony.



PATENTED JUNE 19, 1966.

L KITSEB. TELEPHONY. MPLIGA'HON FILED JuLYza, 1904;

INVENTOR.

NITED STATES PATENT OFFICE.

ISIDUR KITSEE,` 0F PHILADELPHIA, PENNSYLVANIA.

` TELEPHQNY. i

Specification of Lettera Patent.

Patentes .ruse 1e, 1906.

Application filed July 23, 18941 .Serial No. 217,824.

and notwithstanding all improvements made I heretofore in such transmittingdine longdistance transmission is still inadequate for practical rposes. More so is this the case where on y one line is employed'Y and the ground is used as a return. To the retardation and distortion of the double line must in a single line be added the inductive inluence of the neighboring Wires, as well as the difference of potential of the ground near the terminals, and it can be said that whereas the electrical properties of the line itself greatly retard the sound-waves the inductive influence and the difference of potential of the ground drown the Waves generated by the transmitting device, for the reason that the waves of the external disturbances overreach in strength the weak waves generated by the telephonie transmitting device. To over-V come these diculties in the one-line trans-V mission I had recourse to various devices in which thegeerated impulses were capable of inducing secondary impulses of unusual high potential, and to do this it was necessary to ave the secondary of avery large number 0f turns of very iine wire. In fact, i produced devicesi in which the secondary consisted of several'thousand turns of No. 49 wire.

In some of my experiments in which I used a one-line conductor connecting two cities about two hundred and lift miles apart I emplo ed such high-woundy inductoriums 5 but wliercas I was able to'drcwn ali the in ductive noise on the line from the ground, as well as from nei hborin wires, and whereas the` speech cou d be distinctly heard at the receiving-stationif only an ear-phone was inserted in the line at that station speech could not be distinguishedif alike hi h-Wound inductoriums were inserted at bot ends 0f the line. These experiments were re cated on an overhead line of reater lengt than above and with alike resu ts, showing that the generated high impulses are capable of overcorni resistance, ca acity, and self-inductance o the line, as well as inductive iniiuence from neighboring lines or the ground, but

that they cannot overcome the resistance and inductance ofthe high-Wound coil.

If at one of the stations the secondary was shunted when the speech was transmitted from the other station, and vice versa, conimunication could be carried on between these stations, and the speech was distinct and clear; but as soon as the shuntin was.

omitted no speech could be heard in t e receiver. YThe -fart that. the roaring noise heard through the receiver connected in series to the grounded circuit de ends to its greatest extent on the condition o the ground, and that the length of the line has scarcely any inuence on this noise, may not be generally known, but careful experiments have proven such to be the case.

In one of m ex eriments a line of eight miles Vwas em oye This line was in part carried throng cables partial] underground and partiely submarine. he remainder (about four miles) was aerial. The ground was in roximity to the Agrounclsused for telegrapliic lines. The volume of noise was such that conversation could not be carried on between one and the other terminais of these lines. To find outfif this noise was caused-hy the line itself or the ground. orboth, theY ounded part was connected directly to a tee honic receiver and onlyv "about one,-

hal nnle of the line connected to the free tern ruina] Vof said receiver. The noise was not diminishedat all, and even after that `halimile was disconnected the noise onl decreased a trie thus proving that this interference with the transmission of speech is conditioned to the greatest part only on thel ground and is taken up by the terminals of the line in contradstinction to the electrostatic inductionpwhich as is well known, causes the disturbin influence to move from zoo the middle toward t e ends of the line. Y it 'gras also proven in these experiments that an impedance or even a 'resistance per seis ca able of reducing the what I call "ground turbancewif suoli impedance or resistance is inserted between the ground and the receiver, and, further, these ex eriments have proven that the line especial y if the sameis of comparative lug resistance, acts in the same manner as the im edance or resistance inserted between the )line and the ground "los IIO

acts, for when the single line was connected to a second Wire-fthat is,` when a metallic circuit was formed and connected only on one side tothe round--the roaring noise could be heard We l at the grounded Wire but it could be heard only faintly Vat the other end, Where no ground was resent.

To overcome the difficulty ex erienced in 1 a telephonie single line groun ed at both ends, 1t is necessary to arrange ,the receiving instrument in a manner so that between them and the ground devices are placed absorbing the noise due to the ground, and .to do this I have devised an arrangement substantially as illustrated in the drawing, in which is illustrated in .diagrammatic view a telephonie circuit emhodying my improvement. d

In the drawing, A A are two telephonic stations, each equipped with a transmitting and a receiving instrument. These stations are connected together through the line B. Each station consists of the grounded .transmittenpreferably embracing, as is illustrated, the microphonic transmitter F, source of'curren-t E, primary D ,of an inductorinm, .connested locali to ,each other. The secondary D of this in uctorium is connected with one terminal to the ground and with the other terminal to the wire 3. This Wire is connected to the junction .of the wire 1 and 2. l of these wires has an eqnal resistance and is provided with the .device C. These two wires are overbridged :by .Wire ql and have connected thereto 1n series the receiver H. 4To the junction ot' wire 1 and wire 4 ,at each station is connected one ,of the terminals of the line B. To .the u'nction ,of .the wires 2 and 4 are connected devices which? `maire it possible for the operator .to duplicate the electrical conditions ,0f ,the line B, and these devices are designated as an entirety by the letter I, and consist, preferably, of condenser '11, resistance t', and edance fi?. These .devices are grounded I will state that I used in some of my ,experirnents a transmitting ,device wherein the secondary was of such hi imy edance .that -no speech could be translmtted t; lou same when inserted in the line in series. he ad- .vantages of this arrangement for tele honic communication .over a grounded sing e line arez First. An inductorium .of very high intensity can be used Without 4choking .the Second. As atthe one station transmitted impulses will .divide in equal groportion over the branches 1 and 2, it is o .vious that ,the same will not ,operate the home receiver, and it is also .obyious .that in Aoperating the resound which emanates from the groun d. It may ybe fnrther stated that ,careful experiments were made with this arrangement, and whereas is was impossible to telephone over the line with the arrangement as commonly used it was found that hardly any noise due to the ground connection could he distin guished in any of the receivers connected in accordance with my invention.

Having now described my invention, what I ,claim as new, ,and desire to secure hy Letters Patent, s-

l. In a system .of telephonie transmission, two stations connected together through a single conductor, .each station provided with transmitting and receiving instruments, the transmitting instrument consisting of a micro onic transmitter, a sonrce .of current an an inductorium, one .part of said inductoriuin locally connected to said source and.

transmitter and one part of said ,inductorium connected to the ground and to the line with the interposition oit' .two branches of substantially lequal resistance, the telephonie receiver overbridgin said branches, one termi nal of said branches connected to the line proper and one terminal .of said branches connected to devices ,adapted to duplicate the `electrical ,conditions .of said line, said dexvices also grounded.

2. A te ephono system comprising a line connecting two stations with each other, each station organized as follows: two `arms of a bridge, one arm `connected to the line proper .and the other larm connected to an artiiicial line of, electrically considered, about the same value as the main line, leach ,arm ,of the bridge provided with a resistance, .the receiver connected across the bridge-arms, the junction of said bridge-arms connected to `the secondary of` an ,m.ductor,ium, the primary 0f said inductorium .connected locally to a transmitter and source of current.

3. As a means .to overcome the inductive noise 4of the ground on a tele honic line ,of transmission, ,two .conducting ranches connected to the line and ground respectively, a telephonie receiver, said receiver overbridging said branches, and a telephonie transrrutter connected to the junction of said branches and ground.

4. In telephony, a line of transmission .oonnectin together two stations more or less remote om each other, one or both of said Stations provided with a telephonie transmitterconnected stone terminal to the junction of ,two wires ,of substantially equal resistance, a rcoeiveroyerlbridging said branches ceiver at the distant Station those impulses l have to travel over the line, which, as stated l above, acts in port as resistance inserted f between the ground an the receiver a-t the local station, so that the impulses arriving at the `distant station .will he minus` the roaring and resistances connecting one terminal 4of said receiver to the roun 5. A system ,of telephonie communication embracing tWo stations connected together through a conductrngdine, each station em*- bracing a microphonlc transmitter, a' sonrce ofcur'rent and an inductorum, the secon ary IOS IIO

of said inductorium connected with one ter v minal to the ground and with the other terminai to the junction of two circuit branches, each station also rovided with atelephonc receiver overbri ging said branches and means to produce an artificial line.'

6. A telephonie system com rising i two stations connected together to a hne ot transmission, each station embracing two bridgearms, a teiephoni'c receiver across said bridgearxns and a tele honic transmitter operatively related to t e junction of said budgearms.

7. In combination with a oneline telephonic circuit grounded at two stations more Y or less 'remote from each other, a bridge oonneeted with one terminal of one arm to the line and with one'terminal of the `second arm to the ground; the free ends of said two arms connected with Y1the interposition of the secondary of an induetorium to the ground, and a. tel honie receiver overspanning the arms of sei bridge, y

In testimonjr whereof I hereby sign my name, in the presence of two subscribing Wit nesso@ this 21st day of Jul A. D. 1904.

, ISI OR KITSEE. Witnesses:

H. C. YETTER, EDITH R. STILLEY. 

